Single Arm Overhead Tricep Extension

The single arm overhead tricep extension trains the long head of the triceps in its most stretched position, with the upper arm beside the ear and the forearm dropping behind the head. The long head crosses the shoulder joint, so it only reaches full length when the arm is overhead, and no pushdown can reproduce that position however heavy you load it. Working one arm at a time has two benefits: you can use the free hand to hold the working elbow in place, and you can address the strength difference between sides that a two-handed version hides. Sitting with the back supported stops the lower back arching to help. Lower the dumbbell as far as the shoulder comfortably allows and keep the elbow pointing forward rather than letting it flare out to the side.